1. Field of the Invention
The present invention relates generally to aircraft cargo handling apparatus. More particularly, the invention concerns a novel improved braking roller for mounting in a floor mounted roller frame of the character typically installed in aircraft cargo bays to prevent accidental and unintended movement of cargo containers within the cargo compartments during flight and during cargo loading operations.
2. Discussion of the Invention
It is common in cargo transport vehicles such as cargo airplanes to provide a plurality of in-line, floor mounted roller frames which rollably support the cargo containers or unit load devices (ULD's) during cargo loading and unloading operations. As a general rule, the ULDS are quite heavy and as they are rolled toward the forward and rearward bulk heads of the cargo bays it is desirable to provide braking rollers which apply braking forces to the ULDS as they roll rearwardly within the cargo bays. Once the ULDS are in position within the cargo bays or compartments the braking rollers also function to prevent unintended forward movement of the ULD's during flight and preparatory to unloading.
In the past, a number of different types of braking roller devices have been suggested. One such braking roller device is manufactured and sold by Tel Air International Cargo Systems of Hausham, Germany. This braking roller assembly, which is sold under model No. P-N89056, comprises a generally cylindrical shaped ULD engaging outer roller which is rotatably mounted on an elongated shaft that spans a conventional roller frame. Received over the outer shaft is a roller clutch assembly which is freely rotatable relative the shaft in one direction, but is blocked against rotation in an opposite direction. Also mounted on the shaft is a single rotor element which is rotatably driven by the ULD engaging outer roller of the braking device. To resist rotational movement of the rotor, complex and expensive, oppositely canted roller bearings are provided on either side of the rotor. A spring mechanism forces the assemblage made up of the single rotor and the two oppositely canted roller bearings against a radially outwardly extending flange provided on the roller clutch. With this construction, rotation of the cargo engaging roller in one direction is unimpeded. However, rotation of the roller in the opposite direction is controllably resisted by the oppositely canted roller bearings, one of which engages one side of the rotor and the other of which engages the other side of the roller as well as the flange on the roller clutch.
The apparatus of the present invention constitutes a substantial improvement over the Tel Air braking roller assembly and eliminates the use of the costly and somewhat unreliable canted roller bearings. In the improved braking roller assembly of the present invention, two cooperating rotors are mounted on the transverse shaft of the roller frame and four highly novel friction disks cooperate with the dual rotors to control their rotation. These novel friction disks are of a simple construction and take the place of the complex, oppositely canted roller bearings of the Tel Air device.
Unlike the oppositely canted roller bearings of the Tel Air device the novel friction disks of the apparatus of the present invention do not damage the rotors during use and at the same time provide superior braking forces to the pair of spaced apart cooperating rotors of the apparatus, which rotors are driven by a specially configured, improved ULD engaging outer roller element. The improved braking roller apparatus of the present invention thusly provides a device which exhibits superior performance, greater durability and reliability, and superior braking characteristics when compared to competing prior art braking roller assemblies. Additionally, because of its substantially less complex construction, the breaking roller apparatus of the present invention can be manufactured more economically and requires substantially less maintenance than do the prior art braking roller devices.